Metastatic and primary tumors are known to respond differently to chemotherapy. Therefore, when establishing drug efficacy it is important not to rely only on experiments in primary tumor models but to also study the test compound in metastasis models. Organs can favor certain types of primary tumor cells, and therefore it is highly important to test compounds in models that provide the correct microenvironment for the metastases. Bone metastases in particular are a frequent source of pain for late-stage cancer patients and often very resistant to treatment due to the characteristics of the bone. A compound effectively treating or preventing bone metastases may also increase the overall survival.